Parker and Stone, who met in college, developed the show from two animated shorts they created in 1992 and 1995. The latter became one of the first Internet viral videos, which ultimately led to its production as a series. South Park debuted in August 1997 with great success, consistently earning the highest ratings of any basic cable program. Subsequent ratings have varied, but the show remains Comedy Central's highest rated and longest running program. Originally produced by cutout animation, each episode is now created with computer software that emulates the show's distinct style. Episodes are typically written and produced during the week preceding its broadcast, with the vast majority of shows being written, directed, and acted by Parker and Stone. After the first couple of seasons, Parker became the only credited director, and the only writer for the majority of the past four seasons. As of 2011, a total of 216 episodes have aired during the show's fifteen seasons. Parker and Stone are under contract to produce 14 new episodes in 2011. The fifteenth season premiered on April 27, 2011.